Regex, return first match after specific word / Python

Question

EG We have this sentence.

Sample 987 abc sample 567 xyz, yellow world sample 123

By using this regex = sample \d+

I would like, by using re.findall() to get values next to the sample which is after word abc , which is sample 567 and sample 123

I know how to find the value I need, the problem is that I need to use it AFTER a specific word and not sure how to.

PS This word can be changed from abc to word so the result will be sample 123 and etc....

Answer 1

The easiest way might be to limit the regex search to a specific area:

pattern = re.compile(r'sample \d+')
start_pos = original_string.index('your_start_word')
matches = pattern.findall(original_string, start_pos)

Answer 2

Right, it looks like the following may work for you:

\bsample (\d+)(?!.*\babc\b)

This will assure that the word "abc" is not following, therefor it does not capture '987' from your sample.

See the online demo

• \b - A word-boundary.
• sample - Match "sample " literally.
• (\d+) - Capture 1+ digits in a capture group.
• (?..*\babc\b) - Negative lookahead to prevent it be in front of the word "abc".

For example:

import re
s = 'sample 987 abc sample 567 xyz, yellow world sample 123'
results = re.findall(r'(?<=\bsample )\d+(?!.*\babc\b)', s)
print(results)

Prints:

['567', '123']